Air-gas-liquid storage arrangements underground as a means to store energy for subsequent power generation purposes have been previously suggested. Such systems call upon excess electrical capacity during periods of low load requirements to inject a fluid under high pressure into subterranean cavities and then during high load demand periods to subsequently release the compressed fluid to drive electricity generating equipment. However, such systems typically employ cavities which are relatively close to the earth's surface wherein the cavity walls are cool. Hence, such prior systems have of necessity involved high input compression operating costs; while at the same time being attended by high heat losses to the geology ambient to the storage cavity. Such losses require expensive heat replacement inputs, in order to maintain such systems operative as intended. An example of such a previously suggested system is disclosed in U.S. Pat. No. 3,538,340.
It is the object of the present invention to provide an improved pollution-free energy storage system whereby certain disadvantages of previously suggested hydro-air-storage operated systems are obviated; whereby substantial operating economies are effected.